Ottoman Sultan Suleiman I, who has been leading a campaign to take the stronghold of Hapsburg power, Vienna, for his empire, is forced to raise the siege in the face of bad weather, disease and lack of supplies. This offered the opportunity for a great Hapsburg victory as the Ottomans retreated, but a mutiny of his troops renders Ferdinand unable to recapture the city of Buda. As a result, the majority of Hungarian territory is left under the control of Ferdinand's rival, John Zápolya.
Editors. "Ottomans' siege of Vienna is unsuccessful". The Literary Encyclopedia. First published 01 March 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=9987, accessed 27 September 2016.]